1. Field of the Invention
The present invention generally concerns at least the fields of cell biology, molecular biology, and medicine. In particular cases, the present invention concerns methods and compositions related to preparation of induced pluripotent stem cells.
2. Description of Related Art
The factors required to reprogram adult somatic cells to induced pluripotent stem (iPS) cells is an area of intense research. The introduction of defined factors, such as Oct4, Sox2, Klf4, and c-myc, gives rise to the efficient reprogramming of fibroblasts to iPS cells (Takahashi and Yamanaka, 2006). Cells deficient for p53 also show enhanced ability for reprogramming with the addition of Oct4 and Sox2 only (Hong et al., 2009; Kawamura et al., 2009; Li et al., 2009; Marion et al., 2009; Utikal et al., 2009). Unfortunately, overexpression of oncogenes or down regulation of tumor suppressor genes while leading to the generation of cells that are pluripotent can also lead to the production of tumorigenic cells (Li et al., 2009). Consequently, an alternative method for creating iPS cells from somatic cells is desirable.
Both miRNAs and the p53 family member, p63, have been implicated in processes that control stem cell proliferation and cell fate determination (Koster et al., 2004; Mills et al., 1999; Senoo et al., 2007; Su et al., 2009b; Yang et al., 1999). As demonstrated using genetically engineered mice, p63 is critical for the development and maintenance of stratified epithelial tissues (Mills et al., 1999; Yang et al., 1999). Mice lacking p63 cannot form skin, have craniofacial and skeletal defects and die within hours after birth. These defects are partially due to the functions of p63 as a transcriptional regulator of genes involved in multiple processes in skin development including epithelial stem cell proliferation, differentiation, and adhesion (Carroll et al., 2007; Flores, 2007; Ihrie et al., 2005; Koster et al., 2007; Senoo et al., 2007). While it is clear that p63 plays a crucial role in epidermal morphogenesis, its roles as an essential gene in stem cell proliferation and/or differentiation are still not well understood. The controversial roles of p63 in epidermal development are due, at least in part, to the complexity of the gene and existence of multiple isoforms (Yang et al., 2006). There are two major isoforms, those with a transactivation domain (TAp63) that structurally resemble p53 and those lacking this domain (ΔNp63); however, ΔNp63 also transcriptionally regulates unique target genes shown to be involved in limb and epidermal morphogenesis (Cho et al., 2010; Koster et al., 2007).